JP2019159283A - Image projector and mobile body - Google Patents

Abstract

To provide an image projector and a mobile body which can prevent a housing containing the members of an image projector from being heated by entering external light and being broken.SOLUTION: An image projector 500 includes: image generation means 520 for generating a projection image L; an enlargement optical system 511 for enlarging the projection image L generated by the image generation means 520 and projecting the projection image L on a projection surface 401; and a housing 80 containing the image generation means 520 and the enlargement optical system 511. An incident light SL, which enters the enlargement optical system 511 from the outside of the housing 80, propagates in the enlargement optical system 511 in an opposite direction to the direction of the projection image L and is thus collected. The housing 80 has an inner wall surface 80a (80b) in a position other than the region β where the light collecting magnification of the light SL is larger than 15 times.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image projection apparatus and a moving body.

Conventionally, an image generation unit that generates a projection image, a magnifying optical system that magnifies and projects the projection image generated by the image generation unit, and a housing that houses the image generation unit and the magnifying optical system; There is known an image projection apparatus including the above.
For example, Patent Document 1 discloses an estimated temperature of a liquid crystal display device (image generating means) based on the detection result by detecting the intensity of external light propagating in the direction opposite to the display light in the optical path of the display light (projected image). Describes that the output of the backlight of the liquid crystal display device is controlled when the threshold value exceeds a threshold value. In Patent Document 1, when the estimated temperature exceeds a threshold value, the brightness of the backlight of the liquid crystal display device is reduced or turned off to avoid damage to the liquid crystal display device due to the entry of external light as much as possible. It is supposed to be possible.

  However, when external light enters the image projection device, the temperature rises when external light strikes not only the image generation means such as the liquid crystal display device but also the inner wall of the case that accommodates the image generation means and the like. The heat-resistant temperature may be exceeded and the housing may be damaged.

  In order to solve the above-described problems, the present invention provides an image generation unit that generates a projection image, an enlargement optical system that expands the projection image generated by the image generation unit and projects the projection image onto a projection plane, and the image An image projection apparatus comprising: a housing that houses the generating means and the magnifying optical system. Incident light that has entered the magnifying optical system from outside the housing is directed in a direction opposite to the projection image. The inner wall surface of the housing is disposed so as to avoid a region where the incident light condensing magnification exceeds 15 times.

  According to the present invention, there is an excellent effect that the casing that accommodates each member of the image projection apparatus can be prevented from being heated and damaged by the incident external light.

1 is a schematic configuration diagram of a head-up display device according to Embodiment 1. FIG. 1 is a schematic view of an automobile equipped with an automotive head-up display device to which the present invention can be applied. The schematic block diagram of an example of a head-up display apparatus. FIG. 4 is a schematic diagram of a head-up display device in which a configuration related to the image generation unit in FIG. 3 is added. Schematic which shows an example of the optical scanning device of this embodiment. The hardware block diagram of an example of an optical scanning device. The functional block diagram of an example of the control apparatus of an optical scanning device. 6 is a flowchart of an example of processing related to an optical scanning device. The schematic block diagram explaining the malfunction when sunlight injects into a head-up display apparatus. Explanatory drawing about the concept of the optical path prediction of sunlight. The figure which shows the result of the simulation assumed when sunlight injects into one of the prediction optical paths which inject into a head-up display apparatus. The graph which shows the relationship between irradiance and rising temperature. The graph showing the relationship between the distance from the concave mirror and the light collection magnification. The schematic diagram which shows the relationship of the area | region which avoids arrangement | positioning of the concave mirror on the optical path of sunlight, a focal distance, and an inner wall surface. FIG. 5 is a schematic configuration diagram of a head-up display device according to a second embodiment.

Hereinafter, embodiments of a head-up display (HUD) device to which the image projection apparatus according to the present invention can be applied will be described.
As an example, a head-up display device as an image projection device is mounted on a moving body such as a vehicle, an aircraft, or a ship. Then, navigation information (for example, information on speed, travel distance, etc.) necessary for maneuvering the moving body is made visible through the windshield (front windshield) of the moving body. In this case, the windshield also functions as a transmission / reflection member that transmits a part of the incident light and reflects at least a part of the remaining part. Hereinafter, an example will be described in which the head-up display device is mounted on an automobile that is a moving body that includes a windshield and has a configuration that transmits driving of a driving source such as an engine and a motor to driving wheels as a moving unit. .

  FIG. 2 is a schematic view according to an embodiment of an automobile 400 equipped with an automotive head-up display device 500 to which the present invention can be applied. FIG. 3 is a schematic configuration diagram of an example of the head-up display device 500, and FIG. 4 is a schematic diagram of the head-up display device 500 in which a configuration related to the image generation unit 520 of the head-up display device 500 shown in FIG. FIG.

  As shown in FIGS. 2 and 3, the head-up display device 500 is installed, for example, in a dashboard 410 in the vicinity of a windshield (such as a windshield 401) of the automobile 400.

As shown in FIG. 3, the head-up display device 500 includes an image generation unit 520, a projection mirror 511 made of a concave mirror, a cold mirror 70, and a projection housing 80 that accommodates and holds them. The projection housing 80 is provided with an opening through which the projection light L directed toward the windshield 401 passes, and foreign matter enters the projection housing 80 from the outside while transmitting the light. A dustproof window 60 is provided to prevent this.
The projection light L generated by the image generation unit 520 is irradiated to the outside of the projection housing 80 via the cold mirror 70 and the projection mirror 511, enters the windshield 401, is reflected by the windshield 401, and is used by the user. Head to an observer (driver 402). Accordingly, the driver 402 can visually recognize an image or the like projected by the head-up display device 500 as a virtual image I.

The image generation unit 520 includes a light source unit 530, a light deflector 13, a free-form surface mirror 509, an intermediate screen 510, and the like.
As shown in FIG. 4, the light source unit 530 includes three light sources: a red laser light source 501R, a green laser light source 501G, and a blue laser light source 501B. The light source unit 530 includes three collimator lenses, a red collimator lens 502, a green collimator lens 503, and a blue collimator lens 504. Furthermore, the light source unit 530 includes a first dichroic mirror 505 and a second dichroic mirror 506, and is unitized by an optical housing. A light amount adjusting unit 507 is disposed between the light source unit 530 and the optical deflector 13.

  Laser light is emitted from red, green, and blue laser light sources (501R, 501G, and 501B). The emitted laser light passes through collimator lenses (502, 503, 504) provided for each laser light source. Furthermore, the laser light of three colors is synthesized by passing through an incident optical system composed of two dichroic mirrors (505, 506) and a light amount adjusting unit 507, and the synthesized laser light is an optical deflector. 13 toward the reflecting surface 14 and deflected by the optical deflector 13.

The optical deflector 13 is a MEMS (Micro Electro Mechanical Systems) manufactured by a semiconductor process or the like, and the reflection surface 14 is a single minute mirror that swings with respect to two orthogonal axes. A mirror system including two mirrors that swing / rotate with respect to one axis may be used.
The laser beam deflected by the optical deflector 13 is folded back by the free-form surface mirror 509, and a two-dimensional image (intermediate image) is drawn on the intermediate screen 510 that is the surface to be scanned. The projection light L, which is a laser beam deflected by the optical deflector 13, passes through the projection optical system including the free-form surface mirror 509, the intermediate screen 510, and the projection mirror 511, and then is outside the projection housing 80. Projected. As shown in FIG. 4, the intermediate screen 510 is provided with a light receiver 18, and the optical scanning device 10 is adjusted using a light reception signal from the light receiver 18.

  The intermediate screen 510 has a function of diverging the projection light L at a desired divergence angle, and a microlens array structure is preferable. The projection light L emitted from the intermediate screen 510 is incident on the windshield 401 via the projection mirror 511 made of a single concave mirror, and the virtual image I is enlarged and displayed to the driver 402. The projection mirror 511 is designed and corrected so that the horizontal line of the intermediate image formed on the intermediate screen 510 corrects an optical distortion element in which the virtual image I is convex upward or downward due to the shape of the windshield 401. Has been made.

  The head-up display device 500 projects the intermediate image displayed on the intermediate screen 510 onto the windshield 401 of the automobile 400 so that the driver 402 can visually recognize the intermediate image as a virtual image I.

  Each color laser beam emitted from the laser light source (501R, 501G, 501B) is made into substantially parallel light by the collimator lens (502, 503, 504), and is synthesized by the two dichroic mirrors (505, 506). The combined laser light is two-dimensionally scanned by the optical deflector 13 having the reflecting surface 14 after the light amount is adjusted by the light amount adjusting unit 507. The projection light L that has been two-dimensionally scanned by the optical deflector 13 is reflected by the free-form surface mirror 509, corrected for distortion, and then condensed on the intermediate screen 510 to display an intermediate image. The intermediate screen 510 includes a microlens array in which microlenses are two-dimensionally arranged, and expands the projection light L incident on the intermediate screen 510 in units of microlenses.

  The optical deflector 13 reciprocally moves the reflecting surface 14 in the biaxial direction, and two-dimensionally scans the projection light L incident on the reflecting surface 14. The drive control of the optical deflector 13 is performed in synchronization with the light emission timing of the laser light sources (501R, 501G, 501B).

Next, a configuration as an optical scanning device provided in the image generation unit 520 of the present embodiment that forms an intermediate image on the intermediate screen 510 will be described.
FIG. 5 is a schematic diagram illustrating an example of the optical scanning device of the present embodiment.

  As shown in FIG. 5, the optical scanning device 10 optically scans the scanned surface 15 by deflecting the light emitted from the light source device 12 by the reflecting surface 14 of the optical deflector 13 according to the control of the control device 11. A scannable area 16 that is an area that can be optically scanned by the optical deflector 13 includes an effective scan area 17. On the scanned surface 15, a light receiver 18 is provided in the scannable region 16 and outside the effective scan region 17. The optical scanning device 10 includes a control device 11, an optical deflector 13, and a light receiver 18.

  The control device 11 is an electronic circuit unit including, for example, a CPU (Central Processing Unit) and an FPGA (Field-Programmable Gate Array). The light source device 12 is a laser device that emits laser light, for example. The optical deflector 13 is a MEMS device having a reflective surface 14 and capable of moving the reflective surface 14. The scanned surface 15 is the intermediate screen 510 in the image generation unit 520 of the present embodiment. The light receiver 18 is, for example, a PD (Photo Diode) that receives light and outputs a light reception signal. The light source device 12 is the light source unit 530 in the image generation unit 520 of the present embodiment.

  The control device 11 generates control signals for the light source device 12 and the optical deflector 13 based on optical scanning information acquired from an external device or the like, and outputs drive signals to the light source device 12 and the optical deflector 13 based on the control signal. To do. Further, based on the signal output from the light source device 12, the signal output from the optical deflector 13, and the received light signal output from the light receiver 18, synchronization between the light source device 12 and the optical deflector 13 and generation of a control signal are generated. I do.

  The light source device 12 irradiates the light source based on the drive signal input from the control device 11.

  The optical deflector 13 moves the reflecting surface 14 in at least one of the uniaxial direction (one-dimensional direction) and the biaxial direction (two-dimensional direction) based on the drive signal input from the control device 11, and from the light source device 12. To deflect the light. The optical deflector 13 of this embodiment may be at least an optical deflecting unit that deflects in the sub-scanning direction corresponding to the scanning line arrangement direction. Therefore, the optical scanning in both the main scanning direction and the sub scanning direction corresponding to the extending direction of the scanning line may be realized by one light deflecting unit, or the respective optical scanning in the main scanning direction and the sub scanning direction are different. You may implement | achieve by an optical deflection | deviation means. The drive signal is a signal having a predetermined drive frequency. The optical deflector 13 has a predetermined natural frequency (also referred to as a resonance frequency).

  Accordingly, for example, the reflection surface 14 of the optical deflector 13 is reciprocally moved in a biaxial direction within a predetermined range by the control of the control device 11 based on image information which is an example of optical scanning information. An arbitrary image can be projected onto the scanned surface 15 by deflecting the light irradiated from the light source device 12 incident on the reflecting surface 14 and performing optical scanning.

Next, an exemplary hardware configuration of the optical scanning device will be described with reference to FIG.
FIG. 6 is a hardware configuration diagram of an example of the optical scanning device.
As shown in FIG. 6, the optical scanning device 10 includes a control device 11, a light source device 12, an optical deflector 13, and a light receiver 18, which are electrically connected. Among these, the detail of the control apparatus 11 is demonstrated below.

  The control device 11 includes a CPU 20, a RAM 21 (Random Access Memory), a ROM 22 (Read Only Memory), an FPGA 23, an external I / F 24, a light source device driver 25, and an optical deflector driver 26.

  The CPU 20 is an arithmetic device that reads out programs and data from a storage device such as the ROM 22 onto the RAM 21 and executes processing to realize overall control and functions of the control device 11. The RAM 21 is a volatile storage device that temporarily stores programs and data.

  The ROM 22 is a nonvolatile storage device that can retain programs and data even when the power is turned off, and stores processing programs and data that the CPU 20 executes to control each function of the optical scanning device 10. Yes.

  The FPGA 23 is a circuit that outputs control signals suitable for the light source device driver 25 and the optical deflector driver 26 in accordance with the processing of the CPU 20. Further, the output signals of the light source device 12 and the optical deflector 13 are acquired via the light source device driver 25 and the optical deflector driver 26, and further the received light signal is acquired from the light receiver 18, and control is performed based on the output signal and the received light signal. Generate a signal.

  The external I / F 24 is an interface with, for example, an external device or a network. The external device includes, for example, a host device such as a PC (Personal Computer), a storage device such as a USB memory, an SD card, a CD, a DVD, an HDD, and an SSD. The network is, for example, an automobile CAN (Controller Area Network), a LAN (Local Area Network), inter-vehicle communication, the Internet, or the like. The external I / F 24 may be configured to enable connection or communication with an external device, and the external I / F 24 may be prepared for each external device.

The light source device driver 25 is an electric circuit that outputs a drive signal such as a drive voltage to the light source device 12 in accordance with the input control signal.
The optical deflector driver 26 is an electric circuit that outputs a drive signal such as a drive voltage to the optical deflector 13 in accordance with the input control signal.

  In the control device 11, the CPU 20 acquires optical scanning information from an external device or a network via the external I / F 24. Any configuration may be used as long as the CPU 20 can acquire the optical scanning information, and the optical scanning information may be stored in the ROM 22 or the FPGA 23 in the control device 11. Alternatively, a storage device such as an SSD may be newly provided in the control device 11, and the optical scanning information may be stored in the storage device.

  Here, the optical scanning information is information indicating how the scanned surface 15 is optically scanned by the light source device 12 and the optical deflector 13. For example, when displaying an image by optical scanning, Scanning information is image data. For example, when optical writing is performed by optical scanning, the optical scanning information is writing data indicating the writing order and writing location. In addition, for example, when object recognition is performed by optical scanning, the optical scanning information is irradiation data indicating the timing and irradiation range for irradiating light for object recognition.

Next, the functional configuration of the control device 11 of the optical scanning device 10 will be described with reference to FIG.
FIG. 7 is a functional block diagram of an example of a control device of the optical scanning device 10.
The control device 11 according to the present embodiment can realize the functional configuration described below by the instruction of the CPU 20 and the hardware configuration shown in FIG.

  As illustrated in FIG. 7, the control device 11 includes a control unit 30 and a drive signal output unit 31 as functions. The control unit 30 is a control unit realized by, for example, the CPU 20, the FPGA 23, etc., acquires optical scanning information and signals from each device, generates a control signal based on them, and outputs the control signal to the drive signal output unit 31. .

  For example, the control unit 30 acquires image data as optical scanning information from an external device or the like, generates a control signal from the image data by a predetermined process, and outputs the control signal to the drive signal output unit 31. The control unit 30 acquires the output signals of the light source device 12 and the optical deflector 13 via the drive signal output unit 31, and generates a control signal based on the output signals. Furthermore, the control part 30 acquires the light reception signal of the light receiver 18, and produces | generates a control signal based on the acquired light reception signal.

  The drive signal output unit 31 is realized by the light source device driver 25, the optical deflector driver 26, and the like, and outputs a drive signal to the light source device 12 or the optical deflector 13 based on the input control signal. The drive signal output unit 31 functions as an application unit that applies a drive voltage to the light source device 12 or the optical deflector 13, for example. The drive signal output unit 31 may be provided for each target that outputs a drive signal.

  The drive signal is a signal for controlling the drive of the light source device 12 or the optical deflector 13. For example, in the light source device 12, the driving voltage is used to control the irradiation timing and irradiation intensity of the light source. Further, for example, in the optical deflector 13, the driving voltage is used to control the timing and movable range for moving the reflecting surface 14 of the optical deflector 13.

Next, a process in which the optical scanning device 10 optically scans the surface to be scanned 15 will be described with reference to FIG.
FIG. 8 is a flowchart of an example of processing related to the optical scanning device.
In step S11, the control unit 30 acquires optical scanning information from an external device or the like. Further, the control unit 30 acquires the output signals of the light source device 12 and the optical deflector 13 via the drive signal output unit 31 and acquires the light reception signal of the light receiver 18.

  In step S <b> 12, the control unit 30 generates a control signal from the acquired optical scanning information, each output signal, and the received light signal, and outputs the control signal to the drive signal output unit 31. At this time, since each output signal and light reception signal may not be acquired at the time of activation, a predetermined operation may be performed in a separate step at the time of activation.

  In step S <b> 13, the drive signal output unit 31 outputs a drive signal to the light source device 12 and the optical deflector 13 based on the input control signal.

  In step S <b> 14, the light source device 12 performs light irradiation based on the input drive signal. The optical deflector 13 moves the reflecting surface 14 based on the input drive signal. By driving the light source device 12 and the optical deflector 13, light is deflected in an arbitrary direction and optically scanned.

  In the optical scanning device 10 of the present embodiment, one control device 11 has a device and a function for controlling the light source device 12 and the optical deflector 13, but the control device for the light source device and the optical deflector are used. The control device may be provided separately.

  In the optical scanning device 10 of this embodiment, the function of the control unit 30 and the function of the drive signal output unit 31 of the light source device 12 and the optical deflector 13 are provided in one control device 11. These functions may exist separately, and for example, a drive signal output device having a drive signal output unit 31 may be provided separately from the control device 11 having the control unit 30.

Next, a conventional head-up display will be described.
Market expectation is increasing as an application that can recognize alarms and information with few eye movements, and technological development of HUD (head-up display) mounted on vehicles is progressing. In particular, with the development of in-vehicle sensing technology typified by the term ADAS (Advanced Driving Assistance System), vehicles are able to capture various driving environment information and in-vehicle occupant information. HUD is also attracting attention as an “ADAS exit” that conveys this information to the driver.

However, in the severe situation where the midsummer sun just stops and the vehicle stops for a few minutes with a lot of external light (mainly sunlight) entering the inside of the HUD, the display unit such as the image generation unit 520 The temperature may rise excessively. Further, there is a risk that damage such as deformation may occur due to the temperature of the housing exceeding the heat-resistant temperature due to external light focused by, for example, a concave mirror constituting the magnifying optical system.
In recent years, display units caused by external light propagating back through the magnifying optical system as the magnifying optical system mounted inside the HUD increases in magnification and area due to the expansion of the angle of view and display area. The possibility of thermal damage to the housing is further increased.

  Japanese Patent Laid-Open No. 2006-11168 discloses a configuration for preventing troubles when external light enters the HUD, and describes the amount of external light directed to the display unit by a light shielding member provided on the reflection surface side of the reflection mirror. The configuration to be reduced is described. Japanese Patent Laid-Open No. 2005-331624 is provided with a detecting means for detecting the intensity of external light, and when the intensity of incident external light exceeds a predetermined threshold, the external light incident on the reflection mirror is applied to the display unit. A configuration is described in which the reflection mirror is rotated to an angular position where the reflection mirror is not reflected. Further, Patent Document 1 describes a configuration in which the luminance of the backlight light of a display unit composed of a liquid crystal display device is reduced or turned off when the intensity of incident external light exceeds a predetermined threshold. Yes.

  However, in the conventional HUD, a configuration for preventing the temperature from rising due to external light hitting the inner wall of the casing and exceeding the heat-resistant temperature of the casing has not been studied.

FIG. 9 is a schematic configuration diagram for explaining a problem when sunlight SL is incident on the head-up display device 500 to which the present invention shown in FIG. 3 can be applied.
As shown in FIG. 9, the sunlight SL irradiated from the sun 1 passes through the windshield 401 and also passes through the dustproof window 60 and enters the projection mirror 511.

  As shown in FIG. 9, when sunlight SL incident on the head-up display device 500 enters the projection mirror 511, the reflected light reflected by the projection mirror 511 enters the inner wall surface of the projection housing 80 and the image generation unit 520. . The reflected light reflected by the projection mirror 511 that is a concave mirror is condensed, and the irradiance is amplified depending on the distance from the projection mirror 511. This irradiance varies depending on the imaging magnification of the projection mirror 511 and the distance from the projection mirror 511. When the irradiance is amplified and the light whose light energy per unit area is amplified is incident on the inner wall surface of the projection casing 80, the light in the projection casing 80 is irradiated as indicated by “H” in FIG. The part is heated locally. This heating may cause the temperature of the projection casing 80 to partially exceed the heat-resistant temperature and be damaged.

FIG. 10 is an explanatory diagram about the concept of the optical path prediction of sunlight SL.
Depending on the positional relationship between the automobile 400 and the sun 1, sunlight SL enters the head-up display device 500 disposed in the automobile 400 from various angles. The optical path of the incident sunlight SL can be predicted by simulation. Thereby, the angle which may enter into the head-up display apparatus 500 is calculated, and the reach | attainment location which sunlight SL in the components which comprise the head-up display apparatus 500 can reach | attain can be specified.

FIG. 11 is a diagram illustrating a simulation result assuming that sunlight SL is incident on one of the predicted optical paths incident on the head-up display device 500.
“520a” in FIG. 11 is a space in which the image generation unit 520 in the projection housing 80 is arranged. In the example shown in FIG. 11, sunlight SL incident on the projection housing 80 is reflected in the order of the projection mirror 511 and the cold mirror 70, and is reflected again on the projection mirror 511 and hits the inner wall surface 80 a of the projection housing 80. I understand that. In addition, it can be seen that the spot diameter when the sunlight SL is incident on the inner wall surface 80a is smaller than the irradiation diameter when the sunlight SL is incident on the projection mirror 511, and is condensed.

  In the head-up display device 500, when sunlight SL is incident on the driver 402 from the side opposite to the direction in which the virtual image I is projected, the sunlight SL enters the image generation unit 520 and propagates toward the light source unit 530. To do. On the other hand, however, when the sunlight SL is incident from another angle, the sunlight SL reaches other components other than the inner wall surface 80a of the projection housing 80 or the image generation unit 520. The irradiance indicating the density of the light energy at this time varies depending on the condensing magnification by the optical system, and this condensing magnification varies depending on the distance from the converging optical system. And when the condensing magnification is high and the energy when entering the projection mirror 511 is large, the arrival point where the sunlight SL finally reaches is high temperature, which is higher than the heat resistance temperature of the component parts. It can cause damage and loss of strength.

FIG. 12 is a graph showing the relationship between the irradiance and the rising temperature (Δt [° C.]), and is a graph showing a result of simulating the effect on the temperature rise when the irradiance is increased. The material was assumed to be PBT (polybutylene terephthalate).
The melting temperature of PBT is generally about 224 [° C.], and the temperature inside the vehicle when the automobile 400 is left in the hot sun is about 90 [° C.]. Accordingly, the allowable rise temperature Δt is about 110 [° C.] considering the safety factor. From the graph of FIG. 12, the irradiance at a temperature that the material used can withstand is obtained.

From FIG. 12, the irradiance corresponding to the rising temperature Δt of 110 [° C.] is about 4500 [W / m ² ]. Also, AM (air mass) 1.0 assuming the amount of solar radiation just below the equator has an irradiance of 1100 [W / m ² ]. When sunlight SL having an irradiance of 1100 [W / m ² ] is transmitted through the windshield 401 of the automobile 400, the sunlight SL is attenuated to about 40% due to the transmittance of the windshield 401. For this reason, the irradiance of sunlight SL after passing through the windshield 401 is about 440 [W / m ² ]. When the attenuation by the reflection system such as the cold mirror 70 is taken into consideration under the condition that there is no diffusion / condensing from there, when the sunlight SL having an irradiance of 1100 [W / m ² ] is incident, Irradiance of sunlight SL reaching the inner wall surface 80a is about 290 [W / m ² ].

Since the irradiance of sunlight SL reaching the projection housing 80 increases in proportion to the condensing magnification of the magnifying optical system including the projection mirror 511, if the upper limit of the irradiance is 4500 [W / m ² ], The allowable condensing magnification is about 15 times from the following formula (1).
4500 [W / m ² ] / 290 [W / m ² ] = 15.5 [times] (1)

FIG. 13 is a graph showing the relationship between the distance from the concave mirror (projection mirror 511) and the light collection magnification.
As shown in FIG. 13, the light collection magnification varies depending on the distance from the concave mirror, and in a certain range from the concave mirror, in the embodiment, a certain range near the focal point of the concave mirror, the light collection magnification becomes high, and the collected sunlight The energy density (irradiance) of SL increases. If there is an inner wall surface of the projection housing 80 in a certain range near the focal point of such a concave mirror, the projection housing 80 is a molded product made of resin, and therefore is heated by the sunlight SL with increased energy density, When the temperature rises and the melting point is exceeded, thermal damage occurs.

  In FIG. 13, the target condensing magnification is 15 times (dashed line in the figure) or less, and the range in which the condensing magnification is 15 times or more (the range in which the distance from the concave mirror is 300 [mm] to 500 [mm]). “Range in which the light collection magnification increases”. A range slightly outside this range (a range in which the distance from the concave mirror is 280 [mm] to 520 [mm]) is defined as “a range in consideration of variation in assembled parts”. In the present embodiment, this “range in consideration of assembly component variation” is referred to as “region avoiding the arrangement of the inner wall surface” and is expressed as “region β”.

FIG. 14 is a schematic diagram showing the relationship among the concave mirror (projection mirror 511), focal length f, and region β on the optical path of sunlight SL.
Assuming that the diameter of the range on which the sunlight SL hits the concave mirror is “irradiation diameter ω0 on the mirror surface”, and the diameter of the range on which the sunlight SL reflected by the concave mirror is applied to the inner wall surface 80a is “spot diameter ωs”, The light magnification can be represented by “ω0 / ωs”. And if the sunlight SL reflected by the concave mirror has nothing to block, there are places where the condensing magnification is “15 times” in two places on the upstream side and the downstream side in the propagation direction across the focal point. A range between two places is the region β.

In the present embodiment, as shown in FIG. 10, with respect to each sunlight SL incident from various angles, the light collection magnification when the inner wall surface 80a of the projection housing 80 and other structures are irradiated is as follows. It is designed to be 15 times or less, which is the target concentration factor.
Specific design methods are shown in the following (1) to (4).

(1) In the design of the projection housing 80, the inner wall surface 80a is not disposed in the region β in which the condensing magnification of the sunlight SL by the concave mirror (projection mirror 511) is 15 times or more. Thus, by arranging the projection housing 80 and other structures avoiding the position where energy is concentrated at high density, even if the sunlight SL incident on the head-up display device 500 is irradiated on the inner wall surface 80a, The heat dissipation area at the reaching position can be increased and the temperature rise can be suppressed.

(2) When it is unavoidable to place the projection housing 80 or structure in a high-magnification condensing region (region β) where the condensing magnification is 15 times or more due to product and structure restrictions. The light shielding member that shields light before the sunlight SL reaches the inner wall surface 80a is provided. This prevents light from being irradiated on the inner wall surface 80a with high energy density by shielding light in a region where the light condensing magnification is 15 times or less, and suppresses the temperature rise of the projection housing 80. can do.

(3) When the light shielding member has to be disposed in a region where the light condensing magnification is 15 times or more, a high heat resistant member made of a metal material or a resin material having a high melting point is used. Thereby, it can be set as the structure which can endure the high temperature resulting from the sunlight SL of a state with a high energy density being irradiated. In the configuration in which the high heat resistant member is provided, it is desirable to use a high heat conductive member having high thermal conductivity as the high heat resistant member. By using a member having a high thermal conductivity, it is possible to increase the heat radiation efficiency at the time of condensing and suppress the temperature rise.

(4) Further, the cold mirror 70 is arranged in the optical path until the sunlight SL reaches the inner wall surface of the projection housing 80, other structures, or the light shielding member. Thereby, the wavelength component in the infrared band that contributes to heat generation can be cut at a constant rate. Therefore, the energy of the sunlight SL that the sunlight SL reaches the inner wall surface of the projection housing 80, other structures, or the light shielding member can be reduced, and the temperature rise can be suppressed.

As described in (1) to (4) above, by limiting the countermeasures, it is not necessary to form the entire projection housing 80 or the entire other structure with a material having high heat resistance, and the incident sun An increase in cost for a configuration capable of preventing damage due to the optical SL can be minimized.
In this embodiment, as shown in FIG. 10, assuming that the traveling direction of the automobile 400 is “α” and that the sunlight SL is incident from all directions of the automobile 400 facing the traveling direction α. The up display device 500 is simulated. Of the sunlight SL incident on the automobile 400, for the sunlight SL incident on the projection mirror 511, the region β where the converging multiple of the reflected light is about 15 times or more is specified. In the head-up display device 500, when the projection housing 80 or the structure is located in the region β, at least one of the above measures (1) to (4) is taken.

[Example 1]
Next, a first example (hereinafter referred to as “Example 1”) of the present embodiment having at least one configuration of the countermeasures described in the above (1) to (4) will be described.
FIG. 1 is a schematic configuration diagram of a head-up display device 500 according to the first embodiment.
As shown in FIG. 1, a part of sunlight SL that has entered the projection housing 80 from an incident path deviated from the extended line of the optical path of the projection light L is irradiated to the projection mirror 511 constituting the magnifying optical system. There is. The sunlight SL applied to the projection mirror 511 propagates in the opposite direction to the projection light L and is collected by the projection mirror 511. In the first embodiment, as illustrated in FIG. 1, the inner wall surface 80 a of the projection housing 80 is provided avoiding the region β where the concentration factor of the condensed sunlight SL may exceed 15 times. The first embodiment has the above-described configuration (1), and further includes a cold mirror 70 and the above-described configuration (4) as shown in FIG.

  Specifically, when it is continuously formed in accordance with the peripheral inner wall surface 80a, it becomes a position indicated by a broken line “80c” in FIG. 1, but the position of the broken line “80c” is within the range of the region β. Therefore, a part of the inner wall surface 80a is recessed with respect to the peripheral inner wall surface 80a to form an inner wall surface recess 80b, and the shape of the inner wall surface 80a is a region where the condensing magnification of incident sunlight SL exceeds 15 times. Avoided shape. Specifically, the inner wall surface 80a of the projection housing 80 and the entire other structural body are positioned on the optical path of the sunlight SL reflected by the projection mirror 511 and at a position where the distance from the projection mirror 511 corresponds to the region β. The projection housing 80 and other structures are arranged so that is not located.

  The surface of the inner wall recess 80b is irradiated with sunlight SL reflected by the projection mirror 511, but is located outside the region β on the side farther from the focal point of the sunlight SL reflected by the projection mirror 511. Thus, the inner wall surface 80a can be prevented from being located in the region β, the condensing magnification at the position where the sunlight SL is irradiated on the inner wall surface 80a is less than 15 times, and the irradiance (energy density) is set. Can be lowered. As a result, even if a material that does not have a high heat-resistant temperature or a material that does not have high thermal conductivity is used as the projection casing 80, the temperature of the projection casing 80 can be prevented from reaching the melting point that causes thermal damage.

  The portion of the projection housing 80 provided with the inner wall concave portion 80b is in a state where the outer wall surface protrudes outward as shown in FIG. However, by setting only the inner wall surface 80a of the portion overlapping with the region β as the inner wall surface recess 80b, the portion protruding outward can be minimized, and the sunlight SL in a state of high condensing magnification is applied to the inner wall surface 80a. In order to suppress the arrival, the projection casing 80 can be prevented from being enlarged.

[Example 2]
Next, a second example of the present embodiment (hereinafter referred to as “Example 2”) having at least one configuration of the countermeasures shown in the above (1) to (4) will be described.
FIG. 15 is a schematic configuration diagram of a head-up display device 500 according to the second embodiment.
As shown in FIG. 15, a part of sunlight SL that has entered the projection housing 80 from an incident path deviated from the extended line of the optical path of the projection light L is irradiated to the projection mirror 511 constituting the magnifying optical system. There is. The sunlight SL applied to the projection mirror 511 propagates in the opposite direction to the projection light L and is collected by the projection mirror 511. In the second embodiment, as shown in FIG. 15, the sunlight SL is incident on the inner wall surface 80 a of the projection housing 80 located in the region β where the concentration factor of the condensed sunlight SL may exceed 15 times. It is the structure provided with the light shielding member 90 which prevents it.

  In the second embodiment, by providing the light blocking member 90, it is possible to prevent the sunlight SL from being irradiated to the inner wall surface 80a located at a distance included in the region β. Further, as the light shielding member 90, a material (metal or resin having a high melting point) having higher heat resistance than the resin material forming the projection housing 80 is used. By providing the light shielding member 90, it is possible to prevent the sunlight SL from being applied to the inner wall surface 80a located in the region β. For this reason, even if a material that does not have a high heat-resistant temperature or a material that does not have high thermal conductivity is used as the projection casing 80, the temperature of the projection casing 80 can be prevented from reaching the melting point that causes thermal damage.

  By using a material having higher heat resistance than that of the projection housing 80 as the light shielding member 90, the light collection magnification by the projection mirror 511 is high, and even if the light shielding member 90 rises in temperature, it is damaged by the irradiated sunlight SL. Can be prevented. By using a member having higher heat resistance than the projection housing 80, that is, a member having a high melting point as the light shielding member 90, an area where the light shielding member 90 cannot be disposed can be narrowed. For this reason, the degree of freedom in design for arranging the inner wall surface 80a and other components can be improved, and thus the projection housing 80 can be downsized.

  By using a material having higher photothermal conductivity than the projection housing 80 as the light shielding member 90, even if the light condensing magnification by the projection mirror 511 is high, heat is diffused by the light shielding member 90 and the temperature rise can be suppressed. Therefore, even if it is the structure which enlarges the projection image produced | generated by the image generation unit 520 with high magnification and is a structure where a condensing magnification tends to become high, it can prevent that the projection housing | casing 80 is damaged by irradiation of sunlight SL. . Since the temperature rise in the projection housing 80 can be reduced by heat radiation from the light shielding member 90 and the degree of freedom in designing the inner wall surface 80a and other components can be improved, the projection housing 80 can be downsized. Can do.

  In the second embodiment, even when the size and shape of the projection housing 80 cannot be changed due to some restrictions and the inner wall surface 80a cannot be disposed so as to avoid the region β, the light shielding member 90 is disposed, It is possible to prevent the wall surface 80a from being irradiated with sunlight having a high concentration ratio. In addition, a member having at least one of the characteristics that the heat resistance is higher than that of the projection casing 80 and the thermal conductivity is limitedly disposed as the light shielding member 90, which is caused by the incident sunlight SL. The cost increase for the configuration that can prevent the damage can be minimized.

  As described above, in the embodiment, it is assumed that the sunlight SL is incident from all directions, but the energy amount of the sunlight SL when it is incident on the windshield 401 is different depending on the incident angle. Further, the energy amount of sunlight SL when transmitted through the windshield 401 differs depending on the incident angle, and further, the energy amount when incident on the projection mirror 511 also differs. Therefore, the irradiation of the sunlight SL is prevented even in the region where the condensing magnification is 15 times or more on the inner wall surface 80a at the position where the sunlight SL incident from an angle where the amount of energy of the incident sunlight SL is small. Configuration may not be necessary.

  Therefore, a simulation for specifying the region β is performed only for the sunlight SL that is incident on the projection mirror 511 and incident at an incident angle that may cause damage to the projection housing 80 due to heat when the light is collected. You may make it perform. In this case, for sunlight SL incident from an incident angle at which the amount of energy is small, no simulation is performed to calculate a range in which the condensing magnification is 15 times, and the inner wall surface 80a is subjected to a state where the condensing magnification exceeds 15 times. It is assumed that no means for preventing incidence is provided.

  As a configuration for preventing the sunlight SL having a high concentration magnification from entering the inner wall surface 80a, it is conceivable to arrange a duct member so as to cover the optical path of the projection light L. By providing the duct member, the sunlight SL reflected by the projection mirror 511 hits the inner wall surface of the duct member before the concentration magnification is increased and is shielded from light. It can prevent entering into the wall surface 80a. However, in the configuration in which the duct member is provided, the duct member is provided along an optical path having a complicated shape, and it becomes difficult to form the projection casing 80 with a small number of parts, and the projection casing 80 is divided into many parts. Problems can arise that need to be formed. When the number of parts forming the projection housing 80 increases, the assembly accuracy of the image generation unit 520 and the optical system members held by the projection housing 80 may be reduced. Further, since the duct member is provided, the installation position of each member is restricted, and there is a possibility that the degree of freedom in layout of the image generation unit 520 and the members of the optical system is lowered.

  On the other hand, in the present embodiment, the inner wall surface 80a is recessed from the inner wall surface 80a of the projection housing 80 without providing a duct member with respect to a portion where the concentration factor of incident sunlight SL can be 15 or more. Or measures to suppress the temperature rise such as providing the light shielding member 90 are taken. In this way, by limiting the locations where countermeasures are taken, the projection housing 80 can be formed with a small number of parts, manufacturing becomes easy, and assembly accuracy and layout of the image generation unit 520 and optical system members are free. Therefore, the projection casing 80 can be downsized. Further, by forming the projection housing 80 with a main body unit that holds the image generation unit 520 and the optical system member and a lid that covers the opening of the main body unit, the image generation unit 520 and the optical system member are formed. It can be held by a single component (main body), and assembly accuracy can be maintained.

In the present embodiment, an example is shown in which the projection image L is reflected by the windshield 401 of the automobile 400 to cause the driver 402 to visually recognize the projection image, but is not limited thereto.
A combiner (an example of a transparent plate) dedicated to the head-up display device 500 may be provided inside the windshield 401, and the projection image L may be reflected by the combiner so that the driver 402 can visually recognize the projected image.
The head-up display device 500 is not limited to being installed in the dashboard 410, but may be a stationary type that can be installed on the dashboard 410.

  The image generation unit 520 of the above-described embodiment is a laser scanning type image generation unit that forms a projected image by irradiating laser light. The method for forming the projection image is not limited to the laser scanning type, and any method can be used as long as it can form a projection image to be projected onto the projection surface such as the windshield 401 via the magnifying optical system. A liquid crystal display type that displays a projected image in the illumination can also be applied.

  Further, the image projection apparatus is not only an automobile, but also a non-moving body such as a moving robot such as an aircraft, a ship, or a mobile robot, or a working robot that operates a driving target such as a manipulator without moving from the spot. It may be mounted on.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect 1)
An image generation unit such as an image generation unit 520 that generates a projection image such as the projection light L, and an enlargement of a projection mirror 511 and the like that expands the projection image generated by the image generation unit and projects it onto a projection surface such as the windshield 401. In an image projection device such as a head-up display device 500 including an optical system and a housing such as a projection housing 80 that houses an image generation unit and a magnification optical system, the light is incident on the magnification optical system from outside the housing. Incident light such as sunlight SL is condensed by propagating through the magnifying optical system in the opposite direction to the projected image, and avoids areas such as the area β where the condensing magnification of incident light exceeds 15 times. An inner wall surface such as the wall surface 80a is arranged.
According to this, as described in the first embodiment, it is possible to reduce the irradiance by setting the condensing magnification at a position where the incident light is irradiated on the inner wall surface to less than 15 times. As a result, even if a material with a high heat resistance temperature or a material with low heat conductivity is used as the housing, the temperature of the housing can be prevented from reaching the melting point leading to thermal damage.

(Aspect 2)
In aspect 1, a part of the inner wall surface of the housing (such as the inner wall concave portion 80b) is recessed with respect to the peripheral inner wall surface so as to avoid a region where the incident light condensing magnification exceeds 15 times. It is characterized by.
According to this, as described in the first embodiment, it is possible to realize a housing having a shape that avoids a region where the light collection magnification of incident light applied to the inner wall surface exceeds 15 times.

(Aspect 3)
Aspect 1 or 2 is characterized by comprising a light shielding member such as a light shielding member 90 that shields the incident light from reaching an inner wall surface located in a region where the condensing magnification of incident light exceeds 15 times.
According to this, as described in the second embodiment, incident light having a high energy density can be prevented from reaching the inner wall surface of the casing, and thermal damage to the casing can be avoided. Further, the temperature rise inside the casing due to the temperature rise of the casing itself and the heat diffusion from the casing can be reduced.

(Aspect 4)
An image generation unit such as an image generation unit 520 that generates a projection image such as the projection light L, and an enlargement of a projection mirror 511 and the like that expands the projection image generated by the image generation unit and projects it onto a projection surface such as the windshield 401. In an image projection device such as a head-up display device 500 including an optical system and a housing such as a projection housing 80 that houses an image generation unit and a magnification optical system, the light is incident on the magnification optical system from outside the housing. Incident light such as sunlight SL is condensed by propagating through the magnifying optical system in the opposite direction to the projected image, and the inside of the housing located in a region β or the like where the condensing magnification of incident light exceeds 15 times A light shielding member such as a light shielding member 90 that shields incident light from reaching an inner wall surface such as the wall surface 80a is provided.
According to this, as described in the second embodiment, incident light having a high energy density can be prevented from reaching the inner wall surface of the casing, and thermal damage to the casing can be avoided. Further, the temperature rise inside the casing due to the temperature rise of the casing itself and the heat diffusion from the casing can be reduced. Furthermore, by using a heat resistant material for the light shielding member, use of an expensive heat resistant material can be limited to only the light shielding member, and an increase in cost can be minimized.

(Aspect 5)
In the aspect according to any one of aspects 1 to 4, the magnifying optical system has a concave mirror such as the projection mirror 511, and the region where the condensing magnification of incident light exceeds 15 times is obtained after the incident light is reflected by the concave mirror. It is a region having a predetermined range distance (280 [mm] to 520 [mm], etc.) from the concave mirror in the optical path.
According to this, as described in the above embodiment, the region where the light condensing magnification exceeds 15 times can be specified by the distance from the concave mirror, and in the specified region, the incident wall is not irradiated with the incident light. By doing so, the temperature rise of a housing | casing can be suppressed and the thermal damage of a housing | casing can be avoided.

(Aspect 6)
An image generation unit such as an image generation unit 520 that generates a projection image such as the projection light L; an enlargement optical system that enlarges the projection image generated by the image generation unit and projects the projection image onto a projection surface such as the windshield 401; In an image projection apparatus such as a head-up display device 500 provided with a housing such as a projection housing 80 that houses a generating means and a magnifying optical system, the magnifying optical system includes a concave mirror such as a projection mirror 511, and the housing In the optical path after the incident light such as sunlight SL incident on the magnifying optical system from the outside is reflected by the concave mirror, avoid the area such as the area β that is a distance within a predetermined range from the concave mirror. It is characterized by comprising a light shielding member for arranging a wall surface or shielding light so that incident light does not reach an inner wall surface located in the region.
According to this, as described in the above embodiment, by setting the predetermined distance to the vicinity of the focal point of the light reflected by the concave mirror, the energy density is applied to the inner wall surface of the casing located at the predetermined distance. High incident light can be prevented from reaching, and thermal damage to the housing can be avoided.

(Aspect 7)
In any one of modes 3, 4 and 6, the light shielding member is made of a material (metal or the like) having higher heat resistance than the housing.
According to this, as described in the second embodiment, the area where the light shielding member cannot be arranged can be narrowed, and the degree of freedom in designing the arrangement of the inner wall surface and other components can be improved. Can be miniaturized.

(Aspect 8)
In any one of the aspects 3, 4, 6 or 7, the light shielding member is made of a material having higher thermal conductivity than the casing.
According to this, as described in the second embodiment, the temperature rise in the housing can be reduced by heat radiation by the light shielding member, and the degree of freedom in designing the inner wall surface and other components can be improved. The housing can be downsized.

(Aspect 9)
In any one of the first to eighth aspects, the magnifying optical system includes a cold mirror such as the cold mirror 70.
According to this, since the wavelength component in the infrared region contributing to the heat generation in the incident light can be cut as described in the above embodiment, the infrared energy reaching the inner wall surface of the housing or the light shielding member can be attenuated. , Temperature rise can be reduced.

(Aspect 10)
In a moving body such as an automobile 400 provided with a moving means such as a driving source and driving wheels and an image projecting means for projecting an image onto a projection surface such as a windshield 401, any one of aspects 1 to 9 is used as the image projecting means. An image projection device such as a head-up display device 500 according to one aspect is provided.
According to this, as described in the above embodiment, it is possible to realize a moving body including an image projection device that can suppress damage even when sunlight is incident.

DESCRIPTION OF SYMBOLS 1 Sun 10 Optical scanning device 11 Control apparatus 12 Light source device 13 Optical deflector 14 Reflecting surface 15 Scanned surface 16 Scanable area 17 Effective scanning area 18 Light receiver 24 External I / F
25 Light source device driver 26 Optical deflector driver 30 Control unit 31 Drive signal output unit 60 Dustproof window 70 Cold mirror 80 Projection housing 80a Inner wall surface 80b Inner wall surface recess 90 Light shielding member 400 Automobile 401 Windshield 402 Driver 410 Dashboard 500 Head Up-display device 501B Blue laser light source 501G Green laser light source 501R Red laser light source 502 Red collimator lens 503 Green collimator lens 504 Blue collimator lens 505 First dichroic mirror 506 Second dichroic mirror 507 Light amount adjustment unit 509 Free-form surface mirror 510 Intermediate screen 511 Projection Mirror 520 Image generation unit 530 Light source unit f Focal length I Virtual image L Projection light SL Sunlight Δt Rising temperature ω0 Mirror surface irradiation diameter ωs Spot diameter

Japanese Patent No. 6135048

Claims (10)

Image generating means for generating a projected image;
An enlargement optical system for enlarging and projecting the projection image generated by the image generation means onto a projection surface;
In an image projection apparatus comprising: a housing that houses the image generation means and the magnifying optical system,
Region where incident light incident on the magnifying optical system from outside the casing is condensed by propagating through the magnifying optical system in a direction opposite to the projection image, and the condensing magnification of the incident light exceeds 15 times An image projection apparatus characterized in that the inner wall surface of the housing is arranged avoiding the above. The image projection apparatus according to claim 1,
An image projection characterized in that a part of the inner wall surface of the casing is recessed with respect to the surrounding inner wall surface so as to avoid a region where the condensing magnification of the incident light exceeds 15 times. apparatus. The image projection device according to claim 1 or 2,
An image projection apparatus comprising: a light shielding member configured to shield the incident light from reaching the inner wall surface located in a region where the condensing magnification of the incident light exceeds 15 times. Image generating means for generating a projected image;
An enlargement optical system for enlarging and projecting the projection image generated by the image generation means onto a projection surface;
In an image projection apparatus comprising: a housing that houses the image generation means and the magnifying optical system,
Region where incident light incident on the magnifying optical system from outside the casing is condensed by propagating through the magnifying optical system in a direction opposite to the projection image, and the condensing magnification of the incident light exceeds 15 times An image projection apparatus comprising: a light shielding member that shields the incident light from reaching an inner wall surface of the casing located at a position. In the image projection device according to any one of claims 1 to 4,
The magnifying optical system has a concave mirror;
The image projection device characterized in that the region where the condensing magnification of the incident light exceeds 15 times is a region having a predetermined distance from the concave mirror in the optical path after the incident light is reflected by the concave mirror. Image generating means for generating a projected image;
An enlargement optical system for enlarging and projecting the projection image generated by the image generation means onto a projection surface;
In an image projection apparatus comprising: a housing that houses the image generation means and the magnifying optical system,
The magnifying optical system has a concave mirror;
Arranging the inner wall surface of the casing avoiding a region having a predetermined distance from the concave mirror in the optical path after the incident light incident on the magnifying optical system from the outside of the casing is reflected by the concave mirror;
Alternatively, the image projection apparatus includes a light shielding member that shields the incident light from reaching the inner wall surface located in the region. In the image projection device according to any one of claims 3, 4 and 6,
The image projection apparatus, wherein the light shielding member is made of a material having higher heat resistance than the housing. In the image projection device according to any one of claims 3, 4, 6 and 7,
The image projection apparatus, wherein the light shielding member is made of a material having higher thermal conductivity than the casing. In the image projection device according to any one of claims 1 to 8,
An image projection apparatus, wherein the magnifying optical system includes a cold mirror. Transportation means;
In a moving body provided with an image projection means for projecting an image on the projection surface,
A moving body comprising the image projection apparatus according to claim 1 as the image projection unit.

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